The city of Fryn, former capital of it's kingdom, one day came under siege by two large rifts in space. One leading to Avernus, the first layer of the Nine Hells, home of the devils. The Other, leading to the Abyss, where the demons lie. Their eternal war with one another was suddenly brought to the material plane and became the latest battlefield in the everlasting Blood War.

To contain this threat, a chapter of paladins and clerics loyal to the Titan Yuduu were dispatched to the city to quell the danger. Instead, all they found was an unwinnable battle being fought by enemies far stronger then them. So it was decided that they would instead contain the region around the rifts inside an inescapable prison, using a powerful spell called Endless Halls. This was cast in a time when god-like magic could still be known and used by mortals, but at a great cost to themselves, requiring a mass sacrifice of several members of the chapter.

The casting of this spell created the Endless Dungeon, a never-ending imprisonment spell that forever contains the former region of Fryn and all those who lived within it, including the rifts, in an endless series of hallways and rooms that forever traps them in an endless loop. The battle in this dungeon has raged in secret to the outside world for over 2,000 years, both sides stuck in an endless stalemate that neither has any hope of ever winning.